LIVER ROT, COATHE OR BANE. 231 



figure of an inverted cone, with a proboscis-like papilla at the 

 centre of its broad and flat anterior portion. After a few days 

 of free, rapidly-moving existence the young creature loses its 

 cilia and becomes a creeping larva, and thus finds its way 

 into the mollusc which is the first intermediary bearer of the 

 fluke. Thus the life circle is completed, and after the 

 sporo-cyst is formed, the new generation again completes 

 the vicious circle of its existence, provided it finds a suitable 

 host in a sheep. If not, it dies. (Steel.) 



The four stages of fluke disease have been enumerated as 

 follows by Gerlach : 



(1) Traumatic hepatitis, which occurs between June and 

 autumn, is seldom diagnosed but sometimes seen after death 

 from apoplexy. The liver is in a state of acute inflammation. 



(2) Dropsy. The liver pale and firm. Occurs from 

 September to November or December, i.e., six to twelve 

 weeks after invasion. 



(3) Emaciation, the stage of greatest mortality. It occurs 

 in January and February, and the liver is atrophied. 



(4) Migration of the flukes occurs in May and June, but 

 Thomas has evidence of flukes remaining in the sheep longer 

 than a year.* 



When sheep are first invaded by the parasitic sporo-cysts 

 there is a period during which the host appears to be benefited 

 and to accumulate fat. It is for this reason that butchers 

 and graziers sometimes put sheep on to unsound land shortly 

 before slaughtering. It is not necessary to consider this as 

 a stage of the disease, as the action of the flukes may be 

 stimulating to the system, and a small number of flukes 

 have even been held to be beneficial. Rot appears to be due 

 to an excessive number of flukes rather than to the presence 

 of a few, and the complete breaking up of the constitution of 

 the host is due to numbers. In this connection it is well to 

 remind the reader that the flukes are incapable of multiplying 



* Steel, " On Diseases of the Sheep." 



